Condensed, Consolidated Statements of Equity (Unaudited) (USD $) In Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss (Income)	Noncontrolling Interests
Beginning Balances at Dec. 31, 2010	$ 1,009,485	$ 86	$ 347,848	$ 650,253	$ 737	$ 10,561
Beginning Balances, shares at Dec. 31, 2010		86,179
Net income	29,272	0	0	28,839	0	433
Foreign currency translation adjustment	249	0	0	0	249	0
Unrealized gain (loss) on foreign currency, net of tax	116	0	0	0	116	0
Distribution to noncontrolling interests	(415)	0	0	0	0	(415)
Purchase of noncontrolling interests	(612)	0	263	0	0	(875)
Share-based compensation	1,068	0	1,068	0	0	0
Issuance of common stock under stock incentive plans	1,175	0	1,175	0	0	0
Stock Issued During Period, Value, Acquisitions	0
Issuance of common stock under stock incentive plans, shares		239
Stock repurchases	(2,337)	0	(2,337)	0	0	0
Excess tax benefit from stock options	185	0	185	0	0	0
Tax shortfall and other from stock options and awards	(583)	0	(583)	0	0	0
Ending Balances at Mar. 31, 2011	1,037,603	86	347,619	679,092	1,102	9,704
Ending Balances, shares at Mar. 31, 2011		86,418
Beginning Balances at Dec. 31, 2011	1,117,952	87	361,715	745,658	418	10,074
Beginning Balances, shares at Dec. 31, 2011		86,796
Net income	35,811	0	0	35,245	0	566
Foreign currency translation adjustment	927	0	0	0	927	0
Unrealized gain (loss) on foreign currency, net of tax	137	0	0	0	137	0
Distribution to noncontrolling interests	(426)	0	0	0	0	(426)
Share-based compensation	4,183	0	4,183	0	0	0
Issuance of common stock under stock incentive plans	2,621	0	2,621	0	0	0
Stock Issued During Period, Shares, Acquisitions		473
Stock Issued During Period, Value, Acquisitions	10,500	0	10,500	0	0	0
Issuance of common stock under stock incentive plans, shares		229
Stock repurchases	(614)	0	(614)	0	0	0
Excess tax benefit from stock options	187	0	187	0	0	0
Tax shortfall and other from stock options and awards	17	0	17	0	0	0
Ending Balances at Mar. 31, 2012	$ 1,171,295	$ 87	$ 378,609	$ 780,903	$ 1,482	$ 10,214
Ending Balances, shares at Mar. 31, 2012		87,498